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Biomedical subjects

G Bilodeau

Publications and source records attributed to G Bilodeau.

12 recordsLinked to original sources
PubMed2001

Absence of deep-water formation in the Labrador Sea during the last interglacial period.

The two main constituent water masses of the deep North Atlantic Ocean-North Atlantic Deep Water at the bottom and Labrador Sea Water at an intermediate level-are currently formed in the Nordic seas and the Labrador Sea, respectively. The rate of formation of these two water masses tightly governs the strength of the global ocean circulation and the associated heat transport across the North Atlantic Ocean. Numerical simulations have suggested a possible shut-down of Labrador Sea Water formation as a consequence of global warming. Here we use micropalaeontological data and stable isotope measurements in both planktonic and benthic foraminifera from deep Labrador Sea cores to investigate the density structure of the water column during the last interglacial period, which was thought to be about 2 degrees C warmer than present. Our results indicate that today's stratification between Labrador Sea Water and North Atlantic Deep Water never developed during the last interglacial period. Instead, a buoyant surface layer was present above a single water mass originating from the Nordic seas. Thus the present situation, with an active site of intermediate-water formation in the Labrador Sea, which settled some 7,000 years ago, has no analogue throughout the last climate cycle.

Journal Article↗
PubMed1989

Granulocyte elastase-mediated proteolysis of alpha 1-antitrypsin in cystic fibrosis bronchopulmonary secretions.

Airway secretions of patients with cystic fibrosis (CF) contain large amounts of alpha 1-antitrypsin (alpha 1-AT), yet elastase activity is also often detectable, suggesting that airway alpha 1-AT may not be functional in some CF patients. It is unknown whether in CF sputum alpha 1-AT is inactivated by oxidants, neutrophil metalloproteinases, bacterial elastase, or neutrophil elastase. To investigate the mechanism(s) by which alpha 1-AT may be inactivated in CF airway secretions, sputum samples were obtained from nine patients during respiratory physiotherapy. alpha 1-AT was measured by radial immunodiffusion. Sputum-alpha 1-AT was purified by antibody affinity chromatography. Electrophoresis of alpha 1-AT from seven patients with acute infectious exacerbations revealed two distinct components: a minor band corresponding to an elastase/alpha 1-AT complex and a major band typical of proteolysed alpha 1-AT (Mr = 48 kD). Each patient had large amounts of sputum elastase activity. In contrast, two patients without free sputum elastase activity had intact sputum alpha 1-AT; however, alpha 1-AT was partially truncated by porcine pancreatic elastase suggesting that the alpha 1-AT may have been partially oxidized. Adding alpha 1-AT purified from normal serum to alpha 1-AT-depleted sputum containing elastase activity resulted in a small alpha 1-AT/elastase complex with most alpha 1-AT being truncated. The serine proteinase inhibitor phenylmethylsulfonyl fluoride but not the metalloproteinase inhibitor EDTA prevented alpha 1-AT proteolysis, thus granulocyte elastase can mediate alpha 1-AT degradation in CF. Apparently, the large granulocyte elastase burden in some acutely ill patients with cystic fibrosis can proteolytically inactivate alpha 1-AT.

Adolescent↗
PubMed1989

Quartz exposure, retention, and early silicosis in sheep.

The purposes of this study were (1) to investigate the chronology of events in cellular and biochemical changes thought to be important in the development of silicosis, (2) to relate these to changes in lung function and radiograph, and (3) to evaluate the relation of quartz exposure and retention to individual response leading to early silicosis. Thirty-six sheep were exposed by repeated intratracheal infusion at 10-day intervals to 100 mg Minusil-5 in 100 ml saline (Si group), and 10 sheep were exposed at the same intervals to 100 ml saline (control). All sheep were investigated at 3-month intervals by chest radiograph, lung function, and lung lavage. At month 9, chest radiograph score of parenchymal opacities was significantly increased at 2.8 +/- 0.6 versus 0.4 +/- 0.4 in the Si group (p less than .05), establishing early radiologic silicosis. Lung function was significantly altered with reduction in lung compliance, vital capacity, and diffusion capacity (p less than .05). Lung lavage cellularity revealed significant increase in total cells (X 2.5), macrophages (X3), and neutrophils (X3). Albumin in BAL remained at the control level. Fibronectin production was significantly increased, as was the fibroblast growth activity, without significant change in procollagen 3 at this early stage of disease. Total phospholipids were significantly elevated in the Si-exposed sheep, and the profile demonstrated an increase in all the phospholipid components. Spontaneous release of hydrogen peroxide by alveolar cells was not increased, but in the presence of phorbol myristate acetate (PMA) higher levels of peroxide were found in the quartz-exposed sheep (p less than .05). The cellular and biochemical alterations of lung lavage preceded other changes. At month 12, there were good correlations (r greater than .49, p less than .001) between parameters evaluating related phenomena but poor correlations between measurements evaluating different aspects of the disorder. To investigate the heterogeneity in the individual response of sheep to the same exposure (susceptibility), individual quartz retention levels at month 12 were measured and found to correlate well with individual parameters of disease activity. We concluded that in early silicosis of sheep, cellular and biochemical changes in lung lavage preceded derangements of pulmonary function and radiographic abnormalities. Thereafter, parameters of lung lavage, lung function, and radiograph were significantly interrelated, but for a given exposure the degree of quartz retention appeared to determine the intensity of the silicotic process.

Animals↗
PubMed1988

Aluminum inhalation reduces silicosis in a sheep model.

In recent studies, we have documented that the biologic activity of quartz can be substantially reduced by surface chemistry modification with aluminum lactate treatment of the particles. In the present study, we evaluated the efficacy of aluminum lactate inhalation to reduce the biologic activity of experimental silicosis in the sheep tracheal lobe model. Four groups of 10 sheep were exposed once to either 100 ml phosphate-buffered saline (PBS) followed by aerosol inhalation of 10 ml PBS at monthly intervals (PBS-PBS group), to 100 ml PBS followed by inhalation of 100 mg aluminum lactate in 10 ml PBS (PBS-Al group), to 100 mg of quartz in 100 ml PBS followed by inhalation of 10 ml PBS (Si-PBS group), or to 100 mg of quartz in 100 ml PBS followed by inhalation of 100 mg aluminum lactate in 10 ml PBS (Si-Al group). Bronchoalveolar lavage (BAL) was repeated at monthly intervals for 6 months from before exposure (Month 0), and all sheep were autopsied at Month 6. All aerosol inhalations were carried out 24 h after BAL starting at Month 1 and monthly thereafter. In the PBS-PBS group and PBS-Al group, all BAL analyses remained at control levels and lung histology remained normal. In the Si-PBS group, BAL analyses documented significant sustained 3- to 10-fold increases in macrophages, lymphocytes, neutrophils, immunoglobulins, lactate dehydrogenase, glycosaminoglycans, lecithin, and phosphatidylglycerol, with histopathologic changes of nodular silicosis (pathologic score, 2.9 +/- 0.9) and mean retention of quartz at 2.83 +/- 0.98 micrograms/mg lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1987

Cross-reactive monoclonal antibodies to alcohol dehydrogenases.

Three anti-horse liver alcohol dehydrogenase (HLADH) monoclonal antibodies are described. Two are specific for ADH and cross-react with class I and II enzymes from mouse, horse and Chinese hamster. They are specific for the native enzyme but do not inhibit enzyme activity except when combined at high concentration. The third antibody was isolated as a response to rabbit metallothionein. It binds metalloproteins and inhibits ADH activity.

Alcohol Dehydrogenase↗
PubMed1986

Monoclonal antibodies against metallothioneins and metalloproteins.

Monoclonal antibodies against rabbit metallothioneins (MT) were prepared by in vitro immunization of mouse lymphocytes with a mixture of the two forms of metallothionein MT1 and MT2. Six IgM antibodies (TN1,3,4,5,6,7) which bind to metallothionein were characterized. Antibody TN3 is specific for rabbit MT1 and does not react with any other MT's tested. TN5 is specific for both rabbit MT1 and MT2. TN7 is specific for rabbit MT2 but not MT1 and cross-reacts also with Chinese hamster, mouse and rat metallothioneins. The antibodies TN1, TN4 and TN6 bind not only to rabbit MT1 and MT2 but also to other metal binding proteins like alcohol dehydrogenase and carbonic anhydrase.

Antibodies, Monoclonal↗
PubMed1984

Asbestos-related fibrin formation in human plasma.

This study was designed to test the hypothesis that asbestos is responsible for the activation of clotting, for the reduction in activity of clotting factors and for the formation of fibrin when human plasma is exposed to asbestos chrysotile fibers in vitro. The recalcification time was accelerated in the early phase and was found to be greatly prolonged at 24 hours. The activated partial thromboplastin time showed marked changes at 24 hours only. One group of clotting factors, consisting of factors V, IX and X, showed the greatest decrease in their plasmatic activity. The factors least changed were factors XII and VIII; the other clotting factors were found in between these groups. Histologic examination demonstrated fibrin fibers in close proximity to the asbestos. Thus, chrysotile asbestos fibers activate clotting with the subsequent decrease in activity of some coagulation factors resulting in the formation of fibrin.

Adult↗
PubMed1984

Post-myringotomy care: a prospective study.

Children with tympanostomy tubes have always been considered somewhat handicapped in regard to swimming and bathing. Their parents had to maintain constant surveillance to prevent then from getting water in their ears. A prospective study involving more than 1,000 children was conducted between June 1981 and August 1982 on two groups of randomly selected patients to determine the prevalence of suppurative otitis media and its relationship to bathing and swimming. One group had to follow strict rules to prevent water entering the ear (bathing caps, earplugs) whereas the other group was allowed to bathe and swim without any precaution upon the condition of using a polymyxin B/gramicidin ear drop combination at bedtime on the day they swam. The study shows no increase in prevalence of suppurative otitis media in the "open canal" group as compared to the "closed canal" group. Furthermore, the monthly distribution of infections shows a relatively evan distribution throughout the year. This study implies that swimming and bathing are safe for the vast majority of children with tympanostomy tubes and thus simplifies enormously the post-myringotomy care for the child, the parents, and the physician.

Baths↗
PubMed1981

Gel chromatography of heparin.

It is assumed that heparin is a heterogeneous substance. In order to further investigate the purification of heparin, a column chromatographic technique for the fractionation of heparin is described using various diameters of bead form cross-linked dextran gels and an automated apparatus. It was observed that Sephadex G-50 resulted in the separation of three well formed peaks and provided superior resolution compared to all other gels. One of the peaks, representing 51% of the original material, possessed strong anticoagulant activity as measured by the recalcification time, partial thromboplastin time, thrombin time and the anti-Xa test. This peak also possessed strong metachromasia after electrophoresis as well as having a very potent anticoagulant effect in vivo. This technique may have a significant role in the purification of this agent from tissue sources.

Animals↗
PubMed1981

Heparin excretion in intact and hepatectomized rats.

Metabolism and kinetics of 3H-heparin were compared in intact and hepatectomized rats. Rats were divided into three groups: 1) intact rats with biliary fistulas and cystostomies 2) intact rats with only cystostomies and 3) hepatectomized rats with cystostomies. Radioactivity in blood, bile and urine besides anticoagulant activity in blood and urine were examined. In addition, column chromatography of urine was used to isolate possible metabolites. Seventy percent and 80% of the radioactive dose was found in the urine of intact rats at 24 hr and 48 hr. Close to 5% of the radioactivity was found in bile or rats with a biliary fistula after 48 hr. The APTT declined to near normal values at 1 hr whether rats had a biliary fistula or not. In contrast, only 25% of the radioactivity could be exerted into the urine of hepatectomized rats in 24 hr; the APTT did not decline as fast and at 5 hr, it was still 100 seconds. Only one radioactive component could be isolated on chromatography from all urines of these animals and appears to be similar to the original heparin. Thus, the liver has no important role to play in regulating the anticoagulant effects and excretion of heparin.

Animals↗
PubMed1981

Levels of antithrombin III, alpha 2-macroglobulin, and alpha 1-antitrypsin in acute ischemic heart disease.

Since measurements of AT III and other possible coagulation inhibitors might provide an index of hypercoagulability, the goal was to measure over a 3-month period individual changes in blood levels of AT III, alpha 2-microglobulin, and alpha 1-antitrypsin in 51 patients with acute ischemic heart disease who were admitted to a Coronary Care Unit with the following diagnosis: unstable angina (26 patients), acute transmural myocardial infarction (20 patients), or subendocardial myocardial infarction (5 patients). Some patients received prophylactic antithrombotic therapy. AT III was measured by the von Kaulla, Owen, Thrombo-Screen, chromogenic, immunodiffusion, and immunoelectrophoretic methods. Alpha 2-macroglobulin and alpha 1-antitrypsin were measured by immunodiffusion. All inhibitors were measured on three different occasions: (1) on admission to hospital, (1) day of departure from hospital, and (3) at 3 months after hospitalization. Alpha 1-antitrypsin showed a significant increase compared to the control and remained elevated during the 3-month interval. Compared to normal control values, AT III was found to be significantly diminished when measured by one functional method (von Kaulla) in all three blood samples from patients with unstable angina and transmural myocardial infarction and by one immunological method (immunodiffusion) in patients with unstable angina, transmural myocardial infarction, and subendocardial myocardial infarction. Most methods determining functional AT III detected a significant increase 3 months after the acute ischemic episode; this rise was observed more often in patients with myocardial infarction than in those with unstable angina. Stepwise discriminant analysis separated the patients of the three groups. Subcutaneous heparin has no significant effect on AT III levels. Unexplained discrepancies still exist between the results obtained by various functional and immunological methods for determining AT III. It appears, however, that methods measuring functional AT III seem to be more suited than immunological methods to detect changes in AT III levels that might occur during and after an acute episode of ischemic heart disease.

Angina Pectoris↗